Field of the Invention
The invention concerns a telecommunication method, wherein a communication connection, initiated and controlled by the Session Initiation Protocol (SIP) provided by an SIP server, is established to and/or from a communication terminal. The invention further concerns a communication terminal configured such that a communication connection initiated and controlled by the Session Initiation Protocol (SIP) provided by an SIP server can be established to and/or from the communication terminal.
Background of the Related Art
In a communication connection initiated and controlled by the Session Initiation Protocol (SIP), such as a telephone connection, it can be necessary or desirable to call up certain additional functions that are normally provided by servers or network components equipped for that purpose. The Session Initiation Protocol offers corresponding protocol elements only for selected usage circumstances, such as retrieving location coordinates from a server, in this example a header field with a Universal Resource Identifier (URI) for retrieving location coordinates via the HTTP protocol. However, the SIP protocol has no standardized ability to call up preconfigurable functions directly using SIP, regardless of whether or not SIP components are participating in an SIP dialogue. Calling up, also known as addressing, a function of an SIP component participating in the communication connection, whether as part of or outside of the existing SIP dialogue, is not possible in the standard SIP.
A typical application case is calling up a Malicious Call Identification (MCID), which can still be done by the caller shortly after the communication connection is terminated, at the end of the call, for example. In this case, the participating gateway to the communication connection or to the call delays the communication connection or call termination process in the direction of the public network, while in the company network the allocated resources should be released as soon as possible after the end of the SIP dialogue. However, this results in the problem of directing the MCID call-up to the correct gateway and then linking it there with the appropriate communication connection. With known telecommunication methods and corresponding communication terminals, targeted dynamic addressing of the desired function, such as the MCID call-up, is not possible, and addressing the desired function outside of an existing SIP dialogue is rarely possible.